Protective helmet



FIG. 1 is a front elevational view of a protective helmet embodying the new design;

FIG. 2 is a rear elevational view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a botton plan view thereof; and,

FIG. 5 is a right side elevational view thereof, the left side being a mirror image of the right side. 

We claim the ornamental design of a protective helmet, as shown and described. 